The long range goal of this research is to determine the characteristics of different speech production disorders, dysarthrias associated with various neurological diseases. Objective testing, analysis and measurement procedures have been developed and demonstrated to be valid for differentiating the speech production of normal aging adults from that of patients with Parkinson's disease. In addition, these assessment procedures have been demonstrated to be valid measures of changes in speech symptoms associated with the different conditions of hypokinesia and drug induced dyskinesia in Parkinson's disease. The testing procedures include calibration controls, a uniform testing format, and equipment adapted to the special needs of these subjects. Acoustic analyses include spectrographic tracings and graphic sound intensity level recordings. Ongoing studies include: a) Evaluation of the effects of L-Dopa and Bromocriptine on the speech of Parkinson's patients. b) Determination of the speech production disorders associated with Huntington's Chorea, Tardive Dyskinesia, Amyotrophic Lateral Sclerosis and Multiple Sclerosis.